Call the Prime Minister's Office and Government Ministries

Say "Hi" to people at the Prime Minister's Office before retiring to bed every night

Call the Prime Minster's Office (and other government ministries)

Introduce yourself as a concerned Indian citizen calling from the US (or wherever)

Express your dismay at the Cabinet's decision to approve and go ahead with the proposed amendments to the RTI Act

Let them know as an informed citizen of the country, you are very disappointed with the government move, despite widespread criticism from different civil-society groups (tell them how so many people even in the US are actively lodging their protests in order to see that corruption is once and for all rooted out of India)